Straightedge type geometrical instrument



Oct. 1, 1957 F. J. HARDLEY 2,807,879

STRAIGHTEDGE TYPE GEOMETR ICAL INSTRUMENT Filed Jan. 25, 1955 FIG. 4

l6 l7 5 ID A {4| I m i 4,..29L 4% 30 c 32 t 34 FIGS r29 INVENTOR 25 24 26 Frank J. Hordley Will/m 5 2| 6 2O 22 I ATTORNEY United States Patent 3 ce STRAIGHTEDGE TYPE GEOMETRICAL INSTRUMENT V Frank J. Hardley, Bell, Calif. Application January 25, 1955, Serial No. 483,980 1 Claim. or. 33-75 This invention relates to geometrical instruments of the straightedge type and more specifically to an instrument of that type which may be employed as a square, a gauge, a centerhead, a 30 bevel and a 60 bevel.

An importantobject of the invention is to provide such an instrument which may be adjusted for use on members of different thicknesses.

Another important object is to provide such an instrument which permits the use of blade portions containing various indicia and which blade portions are firmly held in place in association with other parts of the instrument when in use, but the blade portions may be readily removed and others substituted when desired.

Still another important object is to provide an instrument as described which comprises few parts and none being helical springs or other delicate parts apt to break or get out of order.

Other objects and advantages of the invention will be apparent during the course of the following detailed description of the invention, taken in connection with the accompanying drawing, forming a part of this disclosure and in which drawing:

Fig. 1 is a top plan of a head portion of the instrument in position to receive a blade portion.

Fig. 2 is a top plan, on a scale reduced over that of Fig. 1 of the head portion with. a blade portion attached thereto and illustrating the instrument being employed as a centerhead.

Fig. 3 is a view partly in side elevation of the instrument and partly in section, in one position for use on material of some thickness.

Fig. 4 is a view in side elevation of the instrument in use on thin material.

Fig. 5 is a vertical section through a fragment of the head portion of Fig. 1 with a blade carried thereby.

In the drawing wherein for the purpose of illustration is shown a preferred embodiment of the invention and where similar reference characters designate corresponding parts throughout the several views, the letter A designates the new instrument and B and C two members, shown by way of illustration, upon which the instrument A is employed.

The instrument A is shown to comprise a head portion 5 and blade portion 6.

The head portion 5 includes a body member which may be a casting, such as of iron, steel, copper or aluminum, having a preferably smooth face 11, an opposite preferably smooth face 12 but of less area than the face 11 since the body member is reduced in thickness, intermediate its mostly arcuate edge 13 and substantially flat outwardly converging edges 14 and 15, to provide two roller-carrying arms 16 and a shoulder 17 which extends from the arms 16 to the face 12. The outer edges 18 and 19 of the arms 16 are in substantial parallelism.

Extending transversely of the body member 10 across the face 11 is a shallow groove 20 having opposite substantially paralleling smooth straight faces 21 and 22 and the bottom face of the groove is also smooth. From Fig.

2,807,879 Patented Oct. 1, 1957 1 it will be noted that the face 22 is spaced an equal'distance from each face 18 and 19 whereupon it is on the transverse center line of the body member. More will be said of the groove 20 in connection with a reference to the blade portion 6. The edge 14 joins the edge 21 to form an angle of substantially 30 and the edge 15 joins the edge 22 to form an angle of substantially 60.

Means 23 to detachably retain a blade portion 6 in the groove 20 comprises a member 24 which may be a short normally flat thin arm of steel, pivoted at one end portion to the bodymember by the pivot pin 25 to slide over the face 11 and'with its free end portion provided with an opening 26 to axially register with a screw threaded opening 27, in the body member 10, when the member 24 bridges the groove 20 as in Fig. 2. Removably extending through the opening 26 is the shank 28 of a thumb screw 29, with the head 30 of the latter adapted to bear upon the outer face of the member 24 (with a washer 31'interposed between the head 30 and member 24) when the shank 28 is screwed into the opening 27.

Carried by the body member 10 are two rollers 32 rotatably carried by the two arms 16. Each arm is provided with a screw threaded opening 33 extending from the face 11 to the opposite faces of the arms, with the axes of the openings 33 spaced a substantially equal distance from the shoulder 17. A suitable pair of hex bolts 34 are adapted to have the screw-threaded portions of their shanks 35 accommodated in the openings 33 and their smooth-surfaced portions extending through axial openings 36 in the rollers 32. A suitable washer 37 is provided for each bolt 34 and roller 32. This arrangement permits the rollers 32 to be selectively positioned, with respect to the body member 10, as in Fig. 3 or as in Fig. 4. Thus, means is provided to detachably secure the rollers to the body member so that the instrument may be adapted to contact the edge of a member B of Fig. 3, or the narrower member C of Fig. 4.

The blade portion 6 may be of any approved kind with characteristics embodying an elongated substantially straight member, having opposite faces 40 and 41, and longitudinal edges 42 and 43 forming the faces 40 and 41. The faces may carry any suitable measuring or gauging indicia.

Referring again to the groove 20, the height of each face 21 and 22 thereof is slightly less than the thickness of the blade portion 6. That is, the height of each face 21 and 22 isslightly less than the width of either edge 42 or 43. For example, the difference may be 5 inch. As a consequence, when the blade portion 6 is within the groove 20, the member 24 will bear tightly against the adjacent face of the blade portion 6 when the thumb screw 29 is screwed down, substantially as in Fig. 5.

The new geometrical instrument may be employed in various ways. With the rollers rolled along the edge of a drafting board, for example, the instrument may be used as a T-square, the rollers permitting easy movement of the instrument. Or the instrument may be employed as a center head as in Fig. 2 or, with the edge 14 or edge 15 against the edge of the drafting board, the instrument may be used as a 30 or 60 bevel. The instrument may be used as in Fig. 2 or on members overhead, or on relatively thick members or, with a change in the relative positions of parts, as in Fig. 4, on relatively thin members whereby the blade portion 6 may hug the surface of the members no matter how thin or thick they may be.

Because of the association of parts as in Fig. 5, the blade portion 6 will not be apt to become accidentally loosened from the head portion 5 since the member 24 bears resiliently against the face of the blade portion 6 and extends fully across the blade portion rather than bears upon or against an edge or edges of the blade portion.

Various changes may be made to the form of the invention herein shown and described without departing from the spirit of the invention or scope of the following claim. v

i What is claimed is: i

A straight edge type geometrical instrument including a blade portion and a head portion, said blade portion having substantially parallel side edges and said head portion including a body member having afiat face, a blade portion-receiving groove opening to said face, extending across said face and having substantially parallel side faces with one of said side faces on the transverse medial line of said body member and in sliding contact with one of. said side edges of said blade portion and the other'of said side faces of said groove being in sliding contact with the other of said side edges of said'blade portion, and said head portion also including two spaced apart substantially parallel arms extending from said body member with two converging outer edges extending from said arms along said body member, one converging edge forming one angle other than a right angle-with said one of said side faces of said groove and the other of said converging edges forming another angle other than a right angle with the other of said side faces of said groove and differing in degrees of are from the degrees of arc of said one angle, and rollers rotatably carried by said arms with their axes of rotation intersecting a line normal to said side faces and disposed an equal distance from the horizontal plane of said one of said side faces, and means carried by one of said portions to detachably secure said portions together with said blade snugly retained within said groove.

References Cited in the file of this patent UNITED STATES PATENTS 82,917 Brooks Oct. 13, 1868 422,852 Traut Mar. 4, 1890 673,687 Penfield May 7, 1901 1,243,568 Steczynski Oct. 16, 1917 1,253,399 Lewis Jan. 15, 1918 1 ,262,434 Beeck Apr. 9, 1918 2,347,659 Burch May 2, 1944 2,354,539 Passick et al. July 25, 1944 

